4 BRITISH LIZARDS 



covery from this third point of view he is describing 

 the Physiology of the animal, or the manner in which 

 the functions are performed during life. This is, 

 again, an immense subject, and he will soon find that 

 he is quite unable to account for all that he sees. 

 But he will also perceive that all the functions which 

 the animal is capable of performing are one of three 

 kinds. They are either concerned with {a) Nutrition, 

 (h) Reproduction, or if neither of these, they are 

 (c) directed to bringing the animal into Relation with 

 the world around it. Every function is one of these 

 three kinds. Breathing by gills, lungs, or the surface 

 of the body is a matter of keeping the body nourished ; 

 so are the various methods adopted by animals to 

 excrete waste products ; so is the circulation of blood ; 

 so is digestion, — all are functions of Nutrition. 



The special means adopted to reproduce offspring 

 constitute the Reproductive functions, whether these be 

 simply growing buds, or more complicated methods. 

 Everything that is not either a nutritive or a re- 

 productive function belongs to the third group of 

 functions, those by which the animal comes into 

 contact with its surroundings. Sight, hearing, touch, 

 smell, taste, consciousness, memory, thought, ideation, 

 and so forth, are all functions of Relation. One cannot 

 conceive of any physiological function which is not 

 directed to one of these three ends. So that our 

 naturalist has now described his animal from three 

 distinct aspects, and, although that has involved much 



